


Sola Dosis Facit Venenum

by OldShrewsburyian



Category: Merlin (TV)
Genre: Bullying, Camelot, Canon Era, Canon-Typical Violence, Father-Son Relationship, Gen, Implied/Referenced Suicide, Intolerance, Introspection, Light Angst, Magic, Magic-Users, Medieval Medicine, Mentions of the following:, No Dialogue, No Plot/Plotless, No Sex, POV Male Character, POV Third Person, Teacher-Student Relationship
Language: English
Status: Completed
Published: 2020-06-07
Updated: 2020-06-07
Packaged: 2021-03-03 22:13:36
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,199
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24582868
Author URL: https://archiveofourown.org/users/OldShrewsburyian/pseuds/OldShrewsburyian
Summary: Set vaguely between the second and third seasons, this character/relationship study is a reflection, from Gaius' point of view, on Merlin, magic, and the uses of fear. I love Gaius a lot, and think he deserves more attention.
Relationships: Gaius & Merlin (Merlin), Gaius & Uther (Merlin), Hunith & Merlin (Merlin), Merlin & Arthur Pendragon (Merlin)
Comments: 11
Kudos: 33





	Sola Dosis Facit Venenum

With nothing to do but watch his alembics, Gaius has time to think about fear. Fear, he knows, is a potent thing. He also knows it to be a necessary one. Fear has kept him alive. Fear is a tool for survival, somewhere between instinct and skill; it kept him from meddling with dark magics as a young man, and it kept him alive even during Uther’s purge. Sometimes fear feels like cowardice, and sometimes it is bitter in his throat, galling as guilt. But most of the time — most of the time — it is only a weight to be borne. Sometimes it is even something that flickers like hope: the fear that has kept him silent is the same fear that allows him to survive and to spread, even within the walls of Camelot’s citadel, the idea that magic is not in itself an evil. Gaius takes his decoction from the heat and pours it into the waiting vials. He will let them cool before stoppering them. 

Since Merlin’s arrival, fear has been different. Somehow, Gaius feels he has never quite gotten over his first breathless shock at seeing the boy there, clad in cheap linens and old leather, gangly and gawking and _magic_. Magic, down to his fingertips. And the helpless fear as he tumbled towards his own destruction was replaced with something between terror and wild joy. 

He had never guessed. He had never thought to fear what Hunith’s boy might be. To give an apprenticeship to an intelligent young man, the son of a friend, that was a service that was easy to give, a favor that carried its own reward. That the boy was a Dragonlord’s son as well… that was something to be remembered, knowledge to be catalogued. It had never occurred to him that Merlin might be something more — more, and profoundly other. 

Even that first day, the boy had been bad at lying. Even conditioned by a lifetime of hiding magic or being mocked for it, he had still had no ready excuse, no glamor ready to be cast on the eyes of the beholder. Gaius sighs, and takes down the dried field cress that is ready to be made into medicines. The seeds in their heart-shaped pods can be ground into powder, used in poultices for the chest. The leaves can be brewed into teas, added to medicines that will soothe the throat and drive away fever. Gaius sighs again. Merlin had been under his care for mere weeks when he had ended up shaking with fever, dying of fever in these rooms, having accused a king of treason.

Gaius shakes his head to clear it. He watches hearts break open under his hands, spilling their contents onto the table, and tries not to think of Merlin, drinking poison with terrible resolve. _Sola dosis facit venenum_ : it is only the amount — or, more precisely, the skill of dosage — that makes the difference between medicine and poison. Gaius has cause to know that well. He knows it from his plants, and he knows it from the potions that can kill or cure. And he knows it from watching Uther. 

Fear has kept Gaius alive. He has watched it kill others. He has watched men and women accused of using magic die, by the pyre and by the axe and by their own hands. Sometimes he thinks it is killing Uther himself. Sometimes he thinks that the king’s fear of magic is like a wasting disease, shrinking the warrior and the statesman to a small-minded miser clinging to his possessions, fearing the future. But such thoughts are treasonous, and Gaius tries not to think them often. Arthur, he thinks, fears both too much and too little, and himself most of all. For his own part, Gaius tries to fear enough and not too much.

Gaius is, without question, most afraid for Merlin. Even after a year and more, the boy is still a mystery to him. His flashes of impish humor are so rare as to be startling — though they are far more suited to a boy of his age than his nights of sleepless study, his long silences, his absences from Camelot that are never fully explained. And Gaius is very much afraid that Merlin, himself, is a comparative stranger to fear. The physician tries to persuade himself that the boy must have known fear, must have grown up with the fear of gibes and taunts, of sticks and stones and the kind of bullies who would hold a scrawny boy’s head underwater for the fun of seeing him thrash. But the idea that Merlin’s magic set him at odds with those around him, made him at once a target and an outcast… that was Hunith’s fear, not the boy’s own.

Sometimes, since coming to Camelot, Merlin has seemed awed by his own powers. Gaius supposes — hopes — that this is not so unlike the experience of any young man coming into his strength. But Merlin is, of course, different. Somewhat to his own surprise, Gaius has never been afraid _of_ Merlin. He knows that he is in the presence of a power unlike that of any other age. He has seen the boy, unconscious, spin magic from his fingers. He has seen him, condemned to death, defy a king. He knows that he has confronted armies and called to dragons. But Merlin himself Gaius has never feared. He knows that he is the only man living who can hope to safely train Merlin both to use magic and to follow a profession where he can use it secretly. He also feels entirely inadequate to the task. 

Merlin has, often, astonished and alarmed Gaius by the seeming insouciance with which he uses magic within the walls of Camelot. But the old man wonders, as he grinds leaves between mortar and pestle, if it might not take a far greater conscious effort on Merlin’s part _not_ to do so. The boy, after all, was born with magic. When it came to magical lore and magical craft, Merlin was all ignorance and eagerness. But when it came to magic itself…. Gaius realizes that he has ground the powder almost too fine, and stops, beginning to parcel it up. Merlin is a revelation and an impossibility, magic part of himself, not a set of skills, as it is for the physician, but something that sparks in his blood, something as essential as breath. And Gaius is afraid for him. 

He can show the boy the lore that has been forbidden and forgotten. He can, when Merlin will allow it, sit with him and comfort him like the child he almost still is, or hold him like the son he never had. He can, always, feed him; and food itself can be a kind of medicine. Gaius tells himself that there must be some benefit to Albion’s most powerful sorcerer in having a place where is treated neither as a servant or a savior, but simply a young man with ordinary needs, as well as extraordinary gifts. He takes a deep breath. Soon, Merlin will return from the day’s tasks. And Gaius must not show fear.

**Author's Note:**

> The medical maxim of the title is often attributed to Paracelsus, but the principle is found in many works of medieval medicine building on the Galenic and Hippocratic traditions.
> 
> This is my first proper fic for the fandom; feedback is appreciated.


End file.
